The overall goal of the ongoing research program is to examine the hypothesis that eicosanoids, a group of biomedically important molecules in mammals which include prostaglandins (synthesized via the enzyme cyclooxygenase) and leukotrienes (synthesized via the enzyme 5- lipoxygenase), have evolutionarily conserved structures, but have physiological functions which involve different mechanisms of action. Despite the fact that mammals have been extensively studied with respect to eicosanoids, relatively little is known about the roles of prostaglandins in non-mammalian vertebrates and only a small body of information, primarily from the laboratory of the Principal Investigator, is available concerning leukotrienes. Poikilothermic vertebrates such as amphibians have physiological and biochemical processes affected by temperature. Changes in membrane composition in response to temperature may affect substrate availability or receptor binding characteristics. This research has give specific aims which include (I) to investigate which blood cell types participate in leukotriene synthesis using cell separation, high performance liquid chromatography and radioimmunoassay (RIA) techniques (II) to investigate eicosanoid production during blood clotting, measuring eicosanoids by RIA (III) to investigate the mechanism of action of leukotrienes in the cardiovascular system of ward and cold-acclimated bullfrogs using cannulated animals, RIA and autoradiography techniques (IV) to investigate the mechanism of action of leukotrienes in the isolated heart and lung of warm- and cold- acclimated bullfrogs using in vitro techniques and measurement of products by RIA and (V) to train minority students in biochemical and physiological research involved in investigating eicosanoids in amphibians. This research, carried out at levels from cellular to whole animal, investigates basic questions concerning biosynthesis and mechanism of physiological action of these biomedically important mediators.